Method of applying refractory covering to skid rail

ABSTRACT

1. In a method of applying low slump refractory material to form an insulating covering on a length of substantially horizontal skid rail cooling pipe having anchoring structure projecting therefrom, the molding of a first section of refractory material in situ around a lower portion of predetermined length of said cooling pipe in surrounding relation to at least a portion of said anchoring structure including the steps of taking a substantially rigid form having a trough, layering a sheet of flexible material against the upper face of said trough, placing the refractory material mix in said trough, advancing said form toward said length of cooling pipe to bring the refractory material mix into engagement with said portion of said anchoring structure, vibrating said from at relatively high speed to permit said form to be easily moved toward said length of cooling pipe and to cause said refractory material mix to completely surround said portion of said anchoring structure, moving said form toward said length of pipe until the refractory material mix is engaged therewith, securing said sheet to said length of cooling pipe, and removing said from whereby said refractory material mix is permitted to continue to harden while held by said sheet, whereby all of the aforementioned steps may be repeated on adjacent lengths of cooling pipe using said form.

Nov. 12,1974 F. w. SCHAEFER METHOD OF APPLYING REFRACTORY COVERING TO SKID RAIL Filed June '7, 1972 AIR VIE/1A TO United States Patent O "ice 3,848,034 METHOD OF APPLYING REFRACTORY COVERING TO SKID RAIL Frank W. Schaefer, 1678 Cory Drive, Dayton, Ohio '45406 Filed June 7, 1972, Ser. No. 260,372

Int. Cl. F27d 1/16 US. Cl. 264-30 2 Claims ABSTRACT OF THE DISCLOSURE The undersides of sections of horizontal pipes in heat treating furnaces are covered With refractory insulation material by a molding process. An air vibrator 18 used to agitate the refractory material mix as the mold is advanced toward the pipe. A liner is used to retain the mix against the pipe as it hardens, whereupon the rigid part of the mold may be immediately reused. The areas of the pipe left exposed are then covered in any suitable fashion such as by troweling.

BACKGROUND OF THE INVENTION This invention relates to a pipe insulation method and more particularly to the molding of castable refractory material to horizontal water cooled pipes for use in heat treating furnaces.

Several methods have been developed to provide insulation for water cooled pipes used in heat treating furnaces. For example, the following US. patents disclose such processes: 2,022,649; 2,436,452 and 2,693,352. Also pertinent to the general problem of applying coverings to pipes or the like are US. Pats. 2,150,830 and 3,020,618.

The known processes are not entirely satisfactory. Processes in which a refractory material mix is applied directly to the pipes and permitted to harden in place have not been generally used because of the difliculty in applying the refractory material to the undersides of the pipes. The use of molds has not been accepted, apparently because of the expense and long furnace down time required.

Until this invention, the preferred procedure for insulating the pipes involved the use of precast refractory material since precast material can be applied to the pipes in a relatively short time. However, precast material is quite expensive. Also, some difficulty has been encountered with the life of precast insulation, apparently due to the fact that an embedded wire mesh is used to anchor the precast material and the wire mesh either provides an insuflicient anchor or there is inadequate cooling of the wire mesh material since much of it is insulated from the water cooled pipe it surrounds.

SUMMARY OF THE INVENTION In accordance with this invention, cooling pipe can be insulated substantially as fast as it can be using precast materials. Suitable metal anchors are connected to the pipe, the anchors thus being cooled and failures thereby minimized. A mixture of refractory material and water is loaded into a substantially semi-cylindrical mold assembly including a rigid form and an inexpensive, flexible liner on the inside face of the form.

As the mold assembly is advanced toward a section of the pipe, the mix is agitated by a vibrator attached to the form. The anchors, therefore, do not impede the movement of the mold assembly toward the pipe. As soon as the mix is in intimate contact with the pipe, the vibration is stopped and the liner is secured to the pipe as by wires and the form removed so that the process may be repeated upon an adjacent section of the pipe. Thereafter the upper portion of the pipe may be insulated by troweling the refractory material thereon.

3,848,034 Patented Nov. 12, 1974 An inexpensive form suitable for use in the method may consist of a piece of sheet material formed as a semicircular trough against which the liner is laid. 'End plates connected to the ends of the trough are provided, the end plates having axially aligned semi-circular recesses with diameters matching the pipe diameters. An air vibrator can conveniently be attached to the center of the underside of the trough.

Utilizing the aforedescribed method and mold assembly two workmen can rapidly and efliciently cover a length of pipe with insulating material. Because liners are used to support the refractory material once it is in place on the pipe, there is only one form needed and the workmen are not delayed while waiting for the refractory material to harden.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a portion of pipe and a skid rail such as is common in heat treating furnaces. The portion of pipe in FIG. 1 is shown provided with anchoring studs.

FIG. 2 is a cross sectional view of the pipe of FIG. 1 and a liner supporting refractory material covering approximately the lower half of the pipe.

FIG. 3 is a view similar to FIG. 2 but showing an alternate mode of attaching the liner to the pipe.

FIG. 4 is a view similar to FIG. 3 after insulating material has been troweled onto the upper portions of the pipe.

FIG. 5 is a side elevational view of the pipe of FIG. 4 shown partially insulated.

FIG. 6 is a side elevational view, with parts broken away and in cross section, of a form in accordance with this invention.

FIG. 7 is a transverse sectional view of the form of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1, a portion of a skid rail 10 is illustrated welded to the top of a horizontal pipe 14 through which coolant water is pumped. In order to anchor refractory material to the pipe 14, plural anchors in the form of headed studs 16 are welded to the outside of the pipe 14. The particular form of studs 16 is unimportant to this invention. For example, pairs of hook-like studs are commonly used for anchors and could be used for this purpose instead of the headed studs 16.

In accordance with this invention, the lower, approximate one-half of a section of the pipe 14 is first covered with a mixture of refractory material and water such as that illustrated at 18 in FIG. 2. While the refractory material is drying, thus hardening, it is supported by a sheet of cardboard or other flexible, inexpensive liner material 20 secured to the pipe 14 by one or more wire strands 22 extended around the pipe and over the top of the skid rail 10. As an alternative, which would be used whenever slabs or the like are supported by the skid rail 10 while the pipe 14 is being covered by refractory material, the ends of the wire strands 22 may be twisted about conveniently accessible studs 16. Such mounting of the liner 20 is illustrated in FIG. 3.

to support the mix after it is secured by the wires 22 to the pipe 14.

Mixtures of refractory material and water suitable for insulating pipes in heat treating furnaces are typically highly viscous and have a low slump similar to concrete mixes. The anchoring studs 16 are essential to retaining the refractory material after it hardens since the hardened material is quite brittle. Any form of anchor, however, presents a problem in that anchors act as abutments preventing the highly viscous refractory mix from being moved into engagement with the surface of the pipe.

The problem presented by the anchors blocking the application of the mix to the underside of the pipe is overcome by agitating the refractory mix as it is being applied. The liner 20 is located in a form 38 to produce a mold assembly. The form 38, which is described in detail below, is provided with a high speed vibrator 54. The mold assembly thus formed is loaded with the refractory mix. As the loaded mold assembly is advanced toward the pipe, the vibrator 54 is energized to agitate the mix. During such agitation or vibration of the mix, the cohesive nature of the mix is apparently so diminished that the form 38 loaded with the mix can be moved toward the pipe 14 during the period of vibration as if there were no anchoring studs 16. It is believed that the vibration or agitation may also hasten the hardening process because it tends to drive the water out of the mix. As soon as the mold assembly and the refractory mix are placed firmly against the pipe, the vibrator 54 is tie-energized. The wires v22 are then secured to the pipe as previously described.

As illustrated in the drawing, it is believed that the agitation of the mix averts the formation of air pockets which otherwise might form in the vicinity of the studs 16.

In practice, after refractory material has been applied to the underside of the first section of pipe 14 and the liner 20 fastened in place to the pipe, refractory material would be applied in the same manner to the underside of a second, adjacent section of pipe, the process being repeated until the refractory material has been applied to the underside along substantially the entire length of the pipe. A new liner is used for each section of pipe, the liner previously used being left in position to permit the mix of refractory material to harden in situ.

Thereafter the upper portions of the pipe 14 between the skid rail 10 and the ledges, designated 180, formed by the exposed upper ends of the molded refractory material 18 are covered with refractory material as indicated at 24 and 26 in FIG. 4. Preferably the portions of refractory material at 24 and 26 are simply troweled onto the portions of the pipe 14 uncovered by material 18.

FIG. shows a length of pipe 14, sections of which have been completely insulated. One end of the pipe in FIG. 5 is shown uncovered so that the relationship of the insulating material to the pipe may be better understood. As noted above, however, the preferred practice would be to first completely cover the lower half of the pipe before covering the upper half. In FIG. 5 it will be noted that the Wires 22 and the liner 20 are left in place. These elements will usually be burned off when the heat treating furnace is in operation.

The middle section of the pipe 14 illustrated in FIG. 5 has been covered with refractory material in the man- 'ner described above. The adjacent section to the right in .FIG. 5 is covered by supporting wire 30, a liner 28, and

refractory mix 32, and refractory material supported, and hidden, by the liner 28. It will be noted that the two liners 20 and 28, and accordingly the refractory mix supported thereby, are separated by a gap 34. A similar gap 36 is formed between the upper portion of material 26 and 32. The gap 34 is formed by the form 38 used in applying the refractory material to the lower half of the pipe. The gap 36 may be formed by routing out the mix with the edge of a trowel. These gaps, which are aligned transversely of the pipe and between each section, serve as expansion gaps to prevent damage to the substantially inelastic, hardened refractory by permitting ilexure of the pipe 14 which typically results from the weight of the slabs to be supported by the skid rails 10.

The form 38 illustrated in FIGS. 6 and 7 consists of an elongate open ended U-shaped trough 40, which determines the contour of the insulating covering and which is made from relatively rigid sheet material or the like having outwardly and longitudinally extending side flanges 42, along its upper edges.- Connected to the ends of the trough are identical end plates 44 and 46. The upper margins of the end plates 44 and 46 have semi-circular recesses designated 48 and 50, respectively, which have substantially the same radius as the radius of the outside of the pipe to which the refractory material is to be appiied. The spacing between the recesses 48, 50 and the upper face of the trough 40 determine the depth or thickness of the refractory material to be applied to the pipe. Of course some allowance must be made for the liner 20' which is laid into the trough over wire strands 22 for the reasons already described.

The air vibrator 54 is connected, as by a clevis 52, to the center of the underside of the trough 40 for vibrating the form 38 and thus agitating the mix 18 as described above. The vibrator 54 must be capable of vibrating the substantial mass of the form 38 and the refractory mix loaded therein at a relatively high vibrational speed. Air vibrators for this purpose are commercially available. For example, vibrators sold under Model AC, capable of operating at approximately 8000 vibrations per minute are useful for this purpose and may be obtained from Cleveland Vibrator Company, 2828 Clinton Ave., Cleveland, Ohio 44113. Such vibrators come in various sizes. For a given application the size would depend upon the mass of the form and the refractory material mix. These factors are in turn dependent upon the diameter of the pipe and the depth of the insulating covering desired.

Any of various refractory compositions may be used in the practice of the process described above. High alumina refractory material such as a product sold under the trade designation Plicast 995 by the Plibrico Company, 1800 Kingsbury St., Chicago, Ill. 60614, is one usable material. The depth or thickness of the insulating layer applied by this process is not critical. A typical thickness would be 1 /2" on a 5" diameter pipe. Preferably the refractory insulation will be essentially the same depth as the length of the anchors and optionally may cover the anchors. The width of the gap 34 is determined by the thickness of the end plates 44, 46. The width is optional; /s" for 1 /2" thick refractory is acceptable.

Although the presently preferred method and apparatus of this invention have been described, it will be understood that various changes may be made within the scope of the appended claims.

Having thus described my invention, I claim:

1. In a method of applying low slump refractory material to form an insulating covering on a length of substantially horizontal skid rail cooling pipe having anchoring structure projecting therefrom, the molding of a first section of refractory material in situ around a lower portion of predetermined length of said cooling pipe in surrounding relation to at least a portion of said anchoring structure including the steps of taking a substantially rigid form having a trough, laying a sheet of flexible material against the upper face of said trough, placing the refractory material mix in said trough, advancing said form toward said length of cooling pipe to bring the refractory material mix into engagement with said portion of said anchoring structure, vibrating said form at relatively high speed to permit said form to be easily moved toward said length of cooling pipe and to cause said refractory material mix to completely surround said portion of said anchoring structure, moving said form toward said length of pipe until the refractory material mix is engaged therewith, securing said sheet to said length of cooling pipe, and removing said form whereby said refractory material mix is permitted to continue to harden while held by said sheet, whereby all of the aforementioned steps may be repeated on adjacent lengths of cooling pipe using said form. t

2. The method of claim 1 wherein said flexible material is connected to said length of cooling pipe by a wire laid between said form and said flexible material when said flexible material is first placed on said trough, the ends of .said wire being connected alternatively either to themselves and around the pipe or to spaced portions of said anchoring structure.

References Cited UNITED STATES PATENTS 3,587,198 6/1971 Hensel 26430 X 3,217,617 11/1965 Wiswell 264338 X 3,328,500 6/1967 Barnctte 264275 X 2,667,664 2/1954 Furell 26472 2,295,420 9/1942 Moore 264262 X 2,693,352 11/1954 Bloom 26432 X 3,646,181 2/1972 Galla 264245 X 1,941,299 12/1933 Greenidge 425--127 2,700,810 2/1955 Garni 26471 X ROBERT F. WHITE, Primary Examiner T. P. PAVELKO, Assistant Examiner US. Cl. X.R. 

1. In a method of applying low slump refractory material to form an insulating covering on a length of substantially horizontal skid rail cooling pipe having anchoring structure projecting therefrom, the molding of a first section of refractory material in situ around a lower portion of predetermined length of said cooling pipe in surrounding relation to at least a portion of said anchoring structure including the steps of taking a substantially rigid form having a trough, layering a sheet of flexible material against the upper face of said trough, placing the refractory material mix in said trough, advancing said form toward said length of cooling pipe to bring the refractory material mix into engagement with said portion of said anchoring structure, vibrating said from at relatively high speed to permit said form to be easily moved toward said length of cooling pipe and to cause said refractory material mix to completely surround said portion of said anchoring structure, moving said form toward said length of pipe until the refractory material mix is engaged therewith, securing said sheet to said length of cooling pipe, and removing said from whereby said refractory material mix is permitted to continue to harden while held by said sheet, whereby all of the aforementioned steps may be repeated on adjacent lengths of cooling pipe using said form. 